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Oxalic Acid Vapor Treatment

Does anyone think that OA vapor treatment should not be done this late in the northeast? I was still seeing adult varroa drops on my BB's in a couple of hives after an early Sept. formic acid treatment and a couple of summer OA vapor treatments. I figure it would be good to beat back the mites now while there is no brood, but is there any reason not to treat with OA at this time of year? Girls were still bringing in pollen prior to Sandy, but not much opportunity for flights since.

Re: Oxalic Acid Vapor Treatment

I did another puff a few days ago when I wrapped. It was around 45 F. with just the odd bee flying. My understanding is it can be done anytime as long as internal hive temperature is above 45 deg. so they are not in and dependant on the cluster. It likely shakes them up a bit and they need a bit of time to re group. I found it amazing how little they seem disturbed by it. Ideally all brood should be emerged so no mites escape under cappings.

Re: Oxalic Acid Vapor Treatment

BeeButler, The key to treating late is to catch the bees broodless or with as little brood as possible so that there are very few Varroa hiding under capped cells and you will get a more effective single treatment mite kill. A good time to treat in your area is toward the end of November or early December whenever you can catch a warm day 45 to 50 degrees when the bees have broken up their cluster a little bit, this will allow the OA vapor to circulate better in the hive thus coating the bees.

Re: Oxalic Acid Vapor Treatment

Just "fogged" my 18 hives today. Took 7 minutes per hive. Used the Heilyser (sp?) vaporizer. Hope that takes care of them for the year. I have a combo of screened and solid bottom boards. On the screen ones I made a sheet metal slide, that when it's all the way in the hive, forms a seal in the front. There is an opening for the vaporizer. On the solid BB, I just slid the vaporizer about 1/2 in and let it vaporize...

Re: Oxalic Acid Vapor Treatment

Hit them now when they're broodless, they'll be fine. The acid will coat everything and kill mites as the cluster moves. Now is the perfect time. Check youtube on how and when the Europeans treat with OA.

Re: Oxalic Acid Vapor Treatment

It's toxic to the mites. The idea is to introduce a chemical that is toxic, but more toxic to the mites than the bees. Properly done, oxalic acid meets that criteria. Now is a pretty good time to apply it.

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